The prior art is replete with digital data communication systems that convey data between system sections or system components. Some data communication systems, such as optical transport networks (OTNs), transmit frame delineated serial streams of digital data, while other systems may transmit format-independent data streams. Conventional SONET/SDH networks transport data frames formatted in accordance with internationally standardized protocols. Generally, a data frame includes a relatively small number of bytes devoted to system overhead (OH), a relatively small number of optional bytes devoted to forward error correction (FEC), and a relatively large number of bytes reserved for the actual client data payload. One specific data frame format utilized by OTNs is the Optical Transport Unit of rate k (OTUK) type set forth in ITU-T Recommendation G.709/Y.1331 (International Telecommunication Union, February 2001). This data frame format is informally referred to as the “digital wrapper” format.
Briefly, each digital wrapper frame contains 16,320 8-bit bytes, six of which form a defined frame alignment signal (FAS) that occurs at the beginning of each frame. Consequently, the FAS provides a periodic pattern of bits that, when detected by a destination component, serves to align the incoming frames. After the destination component establishes frame alignment, it can process the frame data content including the FEC information (when provided) to compensate for network and channel errors. Frame alignment at the signal destination, however, may be difficult or impossible to achieve if channel noise produces a substantial number of erred bits within the data stream (due to the relatively small number of bytes devoted to the FAS). If the destination component fails to achieve frame synchronization, then the FEC information is rendered useless and all system overhead and client data (erred or not) is relegated to an entirely indiscernible state.
The client data payload contained in a data frame structure may contain sensitive, private, or confidential information. For example, the client data may be encrypted at the data source using any number of conventional encryption techniques. The encrypted client data is then formatted in accordance with a particular data framing scheme (e.g., the digital wrapper format) and sent to the destination component, where the client data is decrypted in accordance with the chosen encryption algorithm. Such known techniques, however, are limited to the protection of the client data payload. Furthermore, conventional data frame transmission schemes do not provide for the covert processing of system overhead and/or frame delineation.